The present invention is directed to a tool bit with an axially extending shank arranged to be inserted into a tool chuck of a hand-held tool used for chipping and/or drilling and/or percussion drilling. The shank has at least three axially extending rotary entrainment grooves each of different transverse cross-sections with the grooves being open at a free end of the shank for axial introduction of rotary entrainment means in the chuck. The shank also has an axially extending locking groove closed at its end closer to the end face of the shank for limiting axial movement of the tool bit and for receiving a locking member of the tool bit chuck.
Tool bits of this general type are known, such as set forth in DE-PA 3941646 and DE-PA 4141846. These tool bits have different cross-sections for the rotary entrainment means and they can only be inserted into the tool bit chuck in an angled position.
It would seem to be disadvantageous, however, that the edge surface of the shank located between the locking groove and the rotary entrainment grooves differs greatly in magnitude. Due to the rough operation experienced at construction sites, a crushing or wearing-down of the grooves occurs in the tool bit after prolonged use, with the result that in the remaining wall thickness between the grooves stressed peaks are generated at such locations and result in fatigue failures.